quiet a warning observed when compiling consoletty

The warning was observed during CI build:
[warning]NetHack\sys\windows\consoletty.c(2573,29): Warning C4127: conditional expression is constant

sys/windows/consoletty.c

@@ -2541,6 +2541,9 @@ void early_raw_print(const char *s)
  *
  */
 
+
+DISABLE_WARNING_CONDEXPR_IS_CONSTANT
+
 void nethack_enter_consoletty(void)
 {
     int width;
@@ -2776,6 +2779,8 @@ void nethack_enter_consoletty(void)
 }
 #endif /* TTY_GRAPHICS */
 
+RESTORE_WARNING_CONDEXPR_IS_CONSTANT
+
 /* this is used as a printf() replacement when the window
  * system isn't initialized yet
  */